This application is based upon and claims priority of British Patent Application No. 9807247.3 filed Apr. 3, 1998, the contents being incorporated herein by reference.
1. Field of the Invention
The present invention relates to a method and apparatus for distributing a charge as it falls towards an article.
2. Description of the Related Art
A conventional system for distributing a particulate charge as it falls towards an article is disclosed in U.S. Pat. No. 5,109,760. In the conventional system, a conical screen is supported above a pizza upon which cheese is to be deposited. Cheese particles are dropped in a mass upon the screen and distributed by gravitational force in an even pattern over the pizza. The conical screen has a baffle portion at an upper region of the screen, a circular opening at the apex of the baffle, and a screen with screen openings at a lower region of the screen. The conical screen is mounted in a cylinder with a gap between the outer periphery of the screen and the cylinder. Cheese particles deposited upon the pizza will either have fallen through the opening in the apex of the screen, the screen openings, or the gap between the screen and the cylinder.
An alternative system for distributing a particulate charge is described in U.S. Pat. No. 5,678,476. In this alternative system, a food feed hopper is mounted above a food spreader housing having movable paddles therein and a porous bottom member spaced above the surface upon which the food is to be spread.
A problem with the systems disclosed in U.S. Pat. Nos. 5,109,760 and 5,678,476 is that the particulate charge can be unevenly distributed. In particular, it is difficult to direct product to the center of the article. U.S. Pat. No. 5,109,760 attempts to address this problem by providing a circular opening at the apex of the baffle so that the product in the center falls straight through.
It is an object of the present invention to provide a system for distributing a particulate charge as it falls towards an article.
It is another object of the present invention to provide a baffle, a director and a guide for distributing a particulate charge as it falls towards an article, the director directing at least a portion of the charge radially inwardly onto the baffle, the baffle deflecting the charge outwardly and the guide deflecting the charge inwardly.
Objects and advantages of the present invention are achieved in accordance with a first embodiment of the present invention with an apparatus for distributing a charge falling onto an article, comprising a baffle to deflect at least a portion of the charge radially outwardly; a director arranged upstream of the baffle to direct at least a portion of the charge radially inwardly onto the baffle; and a guide arranged downstream of the baffle to deflect at least a portion of the charge radially inwardly, wherein the charge falls onto and is distributed across the article. The baffle may present a continuous deflection surface to the charge.
Objects and advantages of the present invention are achieved in accordance with a second embodiment of the present invention with a method of distributing a charge falling onto an article, comprising the steps of directing at least a portion of the charge radially inwardly onto a baffle with a director arranged upstream of the baffle; deflecting at least a portion of the charge radially outwardly with a baffle; and deflecting at least a portion of the charge radially inwardly with a guide arranged downstream of the baffle, wherein the charge falls onto the article and is distributed across the article.
The present invention provides an apparatus for and a method of directing a charge toward the center of an article which has advantages over the prior art. For example, U.S. Pat. No. 5,109,760 directs particles towards the center of the article by the provision of an opening in the baffle. In contrast, the present invention deflects a portion of the charge towards the center of the article using a guide arranged downstream of the baffle. The effect of the baffle is enhanced by directing at least a portion of the charge so that it is moving with a radially inward component as it strikes the baffle. This increases the angle of deflection of the baffle.
By deflecting a portion of the charge towards the center of the article using the guide arranged downstream of the baffle a number of advantages are achieved with the present invention. Firstly, the present invention enables the baffle to present a continuous deflection surface to the charge, in contrast to U.S. Pat. No. 5,109,760 where the baffle requires a central opening. As a result, the baffle is more easily constructed, easier to support and easier to clean. Secondly, it has been discovered that surprisingly the distribution can be conveniently controlled by adjusting the relative positions of the baffle and the guide. In contrast, in U.S. Pat. No. 5,109,760 the particle distribution is fixed by the form of the conical screen.
In accordance with the present invention, the baffle may deflect the charge by rotating about a vertical axis. However, the baffle preferably has an outwardly angled deflection surface which deflects the charge radially outwardly. The baffle can then deflect the charge radially without moving.
In accordance with the present invention, the deflection surface can be suitably shaped to provide a desired distribution. For example, if a circumferentially uniform distribution is required (e.g., on a pizza), then preferably the deflection surface is substantially frustoconical.
In accordance with the present invention, the guide and/or baffle are adjustably mounted, wherein the relative positions of the guide and the baffle can be adjusted to achieve a desired distribution. In accordance with an embodiment of the present invention, the baffle is slidably mounted on a baffle support and locking means is provided to lock the baffle at a required position. In accordance with another embodiment of the invention, the baffle has a threaded bore which receives a threaded baffle support and the baffle is moved by screwing it up or down the threaded baffle support.
In U.S. Pat. No. 5,109,760, the conical screen is supported by ledge pins which extend radially towards the screen, and it is not possible to suspend the screen from above since this would obscure the central opening at the apex of the screen. In contrast, in accordance with the present invention, the baffle can be supported by a baffle support which extends towards the baffle from a position upstream of the baffle. Therefore, in accordance with the present invention, the baffle and the baffle support together present the continuous deflection surface to the falling charge. This support arrangement is simple and more sturdy than that disclosed in U.S. Pat. No. 5,109,760.
In accordance with the present invention, the director may comprise a set of air jets which direct the charge radially inwardly onto the chute. Alternatively, the director may comprise a chute having inwardly tapered walls which define a convergence position, wherein the baffle is arranged at least partially upstream of the convergence position.
As a result, at least a portion of the charge is converging as it strikes the baffle. The chute is typically frustoconical, although alternative tapered shapes could be used.
In accordance with the present invention, the chute preferably has an outlet and inwardly tapered walls which define a convergence position, and the baffle is arranged between the outlet and the convergence position and the chute focuses at least a portion of the charge onto the baffle. This focusing of the charge increases the angle of deflection by the baffle, and thus ensures that at least part of the charge is subsequently deflected radially inwardly by the guide and deposited at the center of the article.
In accordance with embodiments of the present invention, the apparatus further comprises a second baffle arranged upstream of the outlet of the chute for deflecting the charge radially outwardly. The second baffle also acts to break up the main mass of the charge.
The guide may be fixed, or the apparatus may further comprise means for moving the guide to and from a masking position adjacent to or abutting with the article whereby the charge falls onto the article with a border defined by the guide. In a preferred embodiment, the guide comprises a fixed outer cylinder and a movable inner cylinder which can be moved to and from the article. The guide and chute may be formed integrally, but preferably they are separated by a gap. This provides access to the interior of the system and enables the relative positions of the guide and chute to be adjusted.
The charge may comprise any suitable charge which can be deflected by the guide and the baffle. The charge is typically particulate and the particles may have a variety of sizes ranging from powdery or granular particles to even larger particles. In a preferred embodiment, the charge comprises particles of food. For example, the charge may comprise breadcrumbs, or a pizza topping such as cheese, pepperoni, mushrooms etc.
The article may be inedible (for example a plate or baking tray) but in a preferred embodiment the article comprises an article of food such as a pizza base.